Biaxially oriented, blown-molded bottles and preform thereof

ABSTRACT

The purpose of this invention is to set the position of the gas barrier layer in such a manner as to solve the problem of decreased accuracy of neck molding dimensions created by the thermal crystallization and the problem of interlaminar separation in the bottom, both of which are associated with the provision of the gas barrier layer. Problems should be solved without being affected by the displacement of the gas barrier layer, which may take place during the co-injection operation of the PET resin layers and the gas barrier layer.  
     A biaxially drawn, blow-molded bottle and its preform comprise at least a layer of a gas barrier material  3  laminated inside the PET resin layers  2,  a functional portion  5  having a screw thread  8  raised spirally in the upper portion of neck  4  and also having a stop ring  6  disposed under the screw thread  8,  and a neck ring  7  disposed at the lower end of the neck  4.  In these preform and bottle, the leading edge  3   a  of the gas barrier layer  3  is positioned at a half height of the neck ring  7  where the most advanced front of the leading edge  3   a  neither reaches a half height of the stop ring  6  nor extends to the functional portion  5.  It is intended here that the neck  4  would not be affected by the shrinking deformation caused by the existence of the gas barrier layer  3  in the functional portion  5  of the neck  4,  which is treated for thermal crystallization.

TECHNICAL FIELD

This invention relates to a biaxially drawn, blow-molded bottle and itspreform having a gas barrier layer laminated inside the wall.

Biaxially drawn, blow-molded bottles made of, e.g., a polyethyleneterephthalate resin (hereinafter referred to as PET resin) have beentrending toward a thinner and thinner wall in recent years, taking thecost aspect into consideration. In order for the drinks filled insidethe bottle to be prevented from getting rotten, there is anever-increasing request for a higher level of gas barrier property forthe bottles with a thin wall.

The secondary molded products in the shape of bottles are given the gasbarrier property in two ways to meet such a request. One method is tomold a primary molded product (hereinafter referred to as preform),which is molded into a bottle and has a laminated structure of PETresin/gas barrier material/PET resin. The other method is toinjection-mold the preform, in which the PET resin is blended with sucha gas barrier material as nylon (MXD-6) and to biaxially draw andblow-mold this preform into a bottle.

The preform of a laminated structure is molded by injecting the PETresin into the mold cavity through the nozzle of an injection-moldingmachine that has been adjusted to a predetermined injection pressure,then injecting a gas barrier material over the PET resin in the cavitythrough the nozzle of another injecting machine, and again injectinginto the cavity the PET resin that has been adjusted to a predeterminedinjection pressure.

Because the gas barrier material does not come in contact with the innermold wall owing to the existence of already injected PET resin, the gasbarrier material keeps a less decreased temperature and remains highlyflowable. Thus, the gas barrier material moves quickly between two PETlayers, and forms a laminated structure of PET/gas barrier/PET.

The flowability of PET resin and gas barrier material inside the cavitychanges depending on various factors, including the temperature of theinjecting machine, injection pressure, injection speed, the differencein viscosity between the resin and the gas barrier material, thepercentage of moisture in the resin, and manifold temperature.Especially, temperatures have a large effect. Even if set temperaturesare specified for the injecting machines, it is difficult to controlprecisely the temperatures of the PET resin and the gas barrier materialinside the injecting machines. The changes in such conditions as theinjection pressure, the injection speed, and the temperature of the gasbarrier material inevitably give rise to a delicate change inflowability. Because of this change, there occurs a phenomenon, in whicha part of the leading edge or the flow front of the gas barrier layermoves toward the mouth from the set position on the circumference of theneck at the time of preform molding while the rest of the leading edgeremains on the body side from the set position. Similarly, on thecircumference of the body, too, a part of the trailing edge or the rearedge of the flow moves upward from the set position while the rest ofthe trailing edge remains on the bottom side of the set position.

The neck of the injection-molded preform is a portion that is not drawnin the secondary molding operation in which the preform is biaxiallydrawn and blow-molded into a bottle. This neck portion is thicker thanany other portions, and has a full gas barrier property with no need ofbeing provided with a gas barrier layer.

However, a problem arises here. If the preform has a laminated structurecomprising PET resin layers and a gas barrier layer, and if the neck ofthe bottle molded from such preform is subjected to whitening (thermalcrystallization), the whitening treatment makes the neck less shrinkabledue to a difference in the degrees of shrinkage between the PET resinand the gas barrier material. As a result, the neck tends to have largerdimensions than the set values after the whitening treatment and to havean elliptic shape. Especially since the functional portion of the neckis not formed as specified, the screw engagement and the seal of the capget out of order.

If the preform of a laminated structure comprising PET resin layers anda gas barrier layer is biaxially drawn and blow-molded into a bottle,there is a problem of damaged transparency and poor outer appearance,which occurs when the PET resin layers and the gas barrier layer peeloff from each other at the bottom of the bottle due to the shock of avertical load, such as the fall of the bottle.

This invention has been made to solve the above-described problems foundin conventional art. The technical problem of this invention is toenable the functional portion of the neck to have the specifieddimensions as precisely as possible in both of the biaxially drawn,blow-molded bottle and its preform having the gas barrier layer in thelaminated structure, with a view to compensating for the gas barrierproperty of the blow-molded bottle. Thus, an object of this invention isto set the position of the leading edge of the gas barrier layer andthereby to solve the problem of changing dimensions of the neck afterthe whitening treatment. Another object of this invention is to solvethe problem of damaged transparency and poor outer appearance, whichoccurs when the PET resin layers and the gas barrier layer peel off fromeach other at the bottom of the bottle due to the shock of a verticalload, such as the fall of the bottle. With this problem solved also bysetting the position of the leading edge of the gas barrier layer, therecan be obtained the biaxially drawn, blow-molded bottle, which can beused comfortably, and its preform to be used to mold such a bottle.

DISCLOSURE OF THE INVENTION

Among the Claims of this invention to solve the above-describedproblems, the means of carrying out the invention of claim 1 exists inthe configuration:

-   that the biaxially drawn, blow-molded bottle comprises at least a    layer of a gas barrier material laminated inside the layers    predominantly made of polyethylene terephthalate, and in addition,    comprises a functional portion having a screw thread raised spirally    in the upper portion of neck and also having a stop ring disposed    under the screw thread and a neck ring disposed at the lower end of    the neck;-   that the leading edge of the gas barrier layer is disposed at a    position of the neck where the most advanced front of the leading    edge does not reach a half height of the stop ring; and-   that the neck is treated for thermal crystallization.

In this invention of claim 1, the leading edge of the gas barrier layeris disposed at the neck position Where the most advanced front of theleading edge does not reach a half height of the stop ring of the neck.Even if the leading edge is somewhat displaced from the set position atthe time of preform molding, the bottle of the laminated structure canbe molded with no leading edge reaching the stop ring and the screwthread, which make up the functional portion of the neck.

Even if the leading edge is somewhat displaced from the set position atthe time of preform molding, there exists no gas barrier layer in thestop ring and the screw thread that make up the functional portion ofthe neck. Therefore, after the whitening treatment of the neck, the heatresistant bottle does not have to face the problem of the neck thatshrinks less and increases in dimensions, because the problem is causedby a difference in the degrees of shrinkage between the PET resin andthe gas barrier material. Instead, the neck can be molded in the rightdimensions as designed.

The means of carrying out the invention of claim 2 includes theconfiguration of claim 1 and also comprises that the leading edge of thegas barrier layer is disposed at the position of the neck where the mostadvanced front of the leading edge does not reach the functionalportion.

In the invention of claim 2, the leading edge of the gas barrier layeris disposed at the neck position where the most advanced front of theleading edge does not reach the functional portion of the neck. Thus,there is no gas barrier layer in the functional portion of the neck,which comprises the stop ring and the screw thread. This functionalportion is varied in its length, depending on the type of bottles,including the bottle having a pilfer-proof function. Therefore in thisinvention, too, the heat resistant bottle does not have to face theproblem of the neck that shrinks less and increases in dimensions, afterthe whitening treatment of the neck, because the problem is caused by adifference in the degrees of shrinkage between the PET resin and the gasbarrier material. Instead, the neck can be molded in the rightdimensions as designed after the whitening treatment.

The means of carrying out the invention of claim 3 includes theconfiguration of the invention of claim 1 or 2 and also comprises thatthe leading edge of the gas barrier layer is disposed at a positionwithin a range of ±7 mm from a half height of the neck ring.

In the invention of claim 3, the standardized preform has a height of 7mm or more from a half height of the neck ring to a half height of thestop ring. The leading edge of the gas barrier layer has also a verticalwidth of displacement in the range of ±7 mm, which is observed when thepreform is injection-molded. For these reasons, the leading edge of thegas barrier layer is set at the position of a half height of the neckring. Thus, it is possible to mold the bottle of a laminated structurein which the most advanced front of the leading edge of the gas barrierlayer neither extends to the functional portion nor reaches a halfheight of the stop ring, which is a part of the functional portion ofthe neck.

The means of carrying out the invention of claim 4 exists in theconfigurations that the biaxially drawn, blow-molded bottle comprises atleast a layer of the gas barrier material laminated with resin layersmainly made of polyethylene terephthalate and that the trailing edge ofthe gas barrier layer is set at the position near the lower end of thebody where the trailing edge does not reach the bottom of the biaxiallydrawn, blow-molded bottle.

In the invention of claim 4, the trailing edge of the gas barrier layeris set at the lower end of the body where this edge does not reach thebottom of the biaxially drawn, blow-molded bottle. Thus, there is no gasbarrier layer at the bottom of the bottle.

Since there exists no gas barrier layer at the bottom of the bottle, thedamaged transparency and poor outer appearance cannot be caused by theseparation of the gas barrier layer from the PET resin layers at thebottom of the bottle even if the bottle experiences the shock of avertical load, such as the fall of the bottle.

The means of carrying out the invention of claim 5 includes theconfiguration of claim 1 to 3, and also comprises that the trailing edgeof the gas barrier layer is disposed in the lower portion of the bodywhere the trailing edge does not reach the bottom of the biaxiallydrawn, blow-molded bottle.

In the invention of claim 5, the leading edge is set at the positionwhere the most advanced front of the leading edge neither reaches a halfheight of the stop ring of the neck nor extends to the functionalportion of the neck, and the trailing edge is set at the position wherethe trailing edge does not reach the bottom. Therefore, after thewhitening treatment, the neck can be molded in the right dimensions asdesigned. In addition, even if the bottle experienced the shock of avertical load, such as the fall of the bottle, the biaxially drawn,blow-molded bottle thus obtained would not have any damaged transparencyand poor outer appearance.

The means of carrying out the invention of claim 6 exists in theconfiguration:

-   that the preform of a biaxially drawn, blow-molded bottle comprises    at least a layer of a gas barrier material laminated inside the    layers predominantly made of polyethylene terephthalate, a    functional portion having a screw thread raised spirally in the    upper portion of the neck and also having a stop ring disposed under    the screw thread, and a neck ring disposed at the lower end of the    neck, which is treated for thermal crystallization; and-   that the leading edge of the gas barrier layer is disposed at a half    height of the neck ring or in the range where the most advanced    front of the leading edge neither reaches a half height of the stop    ring nor extends to the functional portion of the neck.

In the invention of claim 6, the leading edge of the gas barrier layeris set at a half height of the neck ring at the stage of molding thepreform or the primary molded product. When the preform is molded, theleading edge is positioned at a half height of the stop ring or in therange where the most advanced front of the leading edge neither reachesa half height of the stop ring nor extends to the functional portion ofthe neck, even if the most advanced front is somewhat displaced. Thepreform thus obtained has no gas barrier layer in the stop ring and thescrew thread, which make up the functional portion of the neck.

Since there is no gas barrier layer in the functional portion of theneck, the neck can be molded precisely in the specified dimensionswithout causing any such inconvenience as the functional portion havinglarger dimensions than specified, after the whitening treatment of thispreform.

The means of carrying out the invention of claim 7 exists in theconfigurations:

-   that the preform of a biaxially drawn, blow-molded bottle comprises    at least a layer of a gas barrier material laminated inside layers    predominantly made of polyethylene terephthalate, and-   that the trailing edge of the gas barrier layer is disposed in the    lower portion of the body where the trailing edge does not reach the    bottom of the bottle.

In the invention of claim 7, the trailing edge of the gas barrier layeris set at the position where the trailing edge does not reach the bottomof the bottle already at the preform-molding stage. Therefore, even ifthe biaxially drawn, blow-molded bottle experiences the shock of avertical load, such as the fall of the bottle, it is possible to obtainthe preform to be molded into a bottle that is free from damagedtransparency and poor outer appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view, with a partial longitudinal section, showing thepreform of this invention.

FIG. 2 is a graphic diagram showing the changes in the dimensionsmeasured after the whitening treatment in various portions of the neckof (a) the preform made of the PET resin alone, (b) the preform shown inthe embodiment of this invention, and (c) the preform in the comparativeexample.

FIG. 3 is a front view of the bottle in one embodiment of thisinvention, which has been molded from the preform of FIG. 1.

PREFERRED EMBODIMENT OF THE INVENTION

An embodiment of this invention is described, now referring to thedrawings. FIG. 1 shows a front view, with a partial longitudinalsection, of the entire preform 1, which is the primary molded product tobe used to mold the biaxially drawn, blow-molded bottle. The preform 1has a laminated structure comprising a PET resin layer 2—a gas barrierlayer 3—a PET resin layer 2.

The gas barrier material used in this embodiment was a polyamidecontaining m-xylylene diamine (known under the trade name of MXD-6;Mitsubishi Gas Chemical), taking into consideration the gas barrierproperty, the difference in viscosity and the difference in the speed ofcrystallization between the gas barrier material and the PET resin.

As shown in FIG. 1, the preform 1 comprises a functional portion 5,which consists of the screw thread 8 raised on the outer wall in theupper portion of the neck 4 and the stop rings 6 circumferentiallydisposed on the outer wall below the screw thread 8, and also comprisesa neck ring 7 disposed in the lower portion of the neck 4.

Successively downward from the neck 4, the preform 1 comprises thecylindrical shoulder 9, the body 10, and the bottom 11. The bottom 11′of the bottle 1′ is molded from this bottom 11, and includes a groundcontact portion 11 a′ and a concave portion 11 b′.

Preform 1 is molded in such a manner that the leading edge 3 a, theupper end of the gas barrier layer 3, is set at a half height of theneck ring 7.

At the time when the preform is molded, the leading edge 3 a of the gasbarrier layer 3 may be somewhat displaced from the set position of ahalf height of the neck ring 7. Even if such displacement occurs, themost advanced front of the leading edge 3 a does not reach a half heightof the stop ring 6 of the neck 4, but can be positioned within ±7 mmfrom a half height of the neck ring 7.

If the stop ring 6 has a small height as shown in FIG. 1, the mostadvanced front of the leading edge 3 a does not reach a half height ofthe stop ring 6 even if the leading edge 3 a has been displaced.Therefore, the preform 1 that can be molded has no gas barrier layer inthe functional portion 5, which comprises the stop ring 6 and the screwthread 8.

The preform 1 is molded in such a way that the trailing edge 3 b, thelowest end of the gas barrier layer 3, is disposed in the lower portionof the body 10.

As shown in FIG. 3, the trailing edge 3 b of the gas barrier layer 3does not reach the bottom 11′ of the bottle 1′ when the preform 1 hasbeen biaxially drawn and blow-molded into the bottle 1′. The bottom 11′of the bottle 1′ is defined as the portion comprising the ground contactportion 11 a′ and the concave portion 11 b′, including the curved areaof the ground contact portion 11 a′.

The above-described preform 1 was molded by the co-injection moldingmethod, and its neck 4 was treated for whitening. After the treatment,the preforms thus obtained were put to a test for the dimensionalchanges in various portions of the neck 4. FIG. 2 shows the results.

FIG. 2 shows the dimensional changes in various portions of the neck,which have been measured after the whitening treatment, in which themeasurements were made by using (a) the preform molded by the PET resinalone (control), (b) the preform of this invention, in which the leadingedge 3 a has not reached a half height of the stop ring 6 (thisinvention), and (c) the preform in which the leading edge has reached aposition higher than the stop ring 6 (a comparative example). In FIG. 2,vertical axis indicates the dimensional difference, Δd, for the preform(b) and the preform (c), as compared with the preform (a); and thehorizontal axis indicates the points of measurements, P, for eachpreform.

As shown in FIG. 2, the preform (b) showed little change in the outerdiameter (5) of the screw thread 8 that belonged to the functionalportion 5 of the neck 4, the outer diameter (6) of the stop ring 6, theouter diameter (7) in the lower part of the stop ring 6, and the outerdiameter (8) of the neck ring 7, as compared with the preform (a). Thus,the test proved that after the whitening treatment, the neck 4 had beenmolded in almost the same dimensions as designed.

The preform (b) also showed little change in (1) the height of thefunctional portion 5 ranging from the stop ring 6 to the bottle mouth 4a and (2) the neck height ranging from the neck ring 7 to the bottlemouth 4 a, as compared with the preform (a) that was molded with the PETresin alone, thus proving that there is no change in the extent ofshrinkage for the neck 4.

On the other hand, the neck of the preform (c) had the leading edge at aposition higher than the stop ring 6 and showed larger measurements thanin the neck of preform (a) made of PET alone, especially in such itemsas the outer diameter (5) of the screw thread 8 in the functionalportion 5, the outer diameter (6) of the stop ring 6, the outer diameter(7) in the lower part of the stop ring 6, and the outer diameter (8) ofthe neck ring 7, after the whitening treatment. Thus, it can beconfirmed that after the whitening treatment, the neck 4 becomes lessshrinkable and has larger dimensions than the set values and is unableto have the right dimensions as designed, due to the difference in thedegrees of shrinkage between the PET resin and the gas barrier layer 3,which has the leading edge 3 a at a position higher than the stop ring6.

The neck of the preform (c), with the leading edge 3 a extending to aposition higher than the stop ring 6, has fairly larger dimensions thanthe neck of the preform (a) in such items as (1) the height of thefunctional portion 5 ranging from the stop ring 6 to the bottle mouth 4a and (2) the neck height ranging from the neck ring 7 to the bottlemouth 4 a. Since the leading edge 3 a of the gas barrier layer 3 hasreached the functional portion 5 of the neck 4, it can be clearlyconfirmed that the whitening treatment makes the neck less shrinkable.

From the results shown in FIG. 2 it could have been confirmed that afterthe whitening treatment, the neck 4 can be molded precisely in the samedimensions as designed for the preform 1 in which the leading edge 3 aof the gas barrier layer 3 has been set at a half height of the neckring 7 so that even the most advanced front of the leading edge 3 awould not reach a half height of the stop ring 6, which is a part of thefunctional portion 5 of the neck 4.

The above-described preform 1 was biaxially drawn and blow-molded intothe bottle 1′. The bottle was filled with a liquid and was put to a testin which a vertical load was applied to the bottle. A gas barrier layer3 with a content of 5.1 wt. % and a thickness of 35 μm was used, and thetrailing edge 3 b of this gas barrier layer was set in the lower portionof the body 10. The preform 1 having such a gas barrier layer 3 wasbiaxially drawn and blow-molded into a 500-ml bottle 1′ for the test.

The test with the bottle 1′ confirmed that the gas barrier layer 3 andthe PET resin layers 2 did not break away from each other up to a forceof 661.5N at which the bottle 1′ buckled.

From the results of this test it has been confirmed that the PET resinlayers 2 and the gas barrier layer 3 are not broken away from each otherand that there is neither damaged transparency nor poor outerappearance, which would occur if the gas barrier layer 3 were brokenaway from the PET resin layers 2. Actually such separation does notoccur unless an outside shock, if any, caused by a vertical load, suchthe fall of the bottle 1′, is strong enough to buckle the bottle 1′.This is because there is no gas barrier layer 3 in the bottom 11′ of thebottle 1′, which is molded from the preform 1 that has been molded bysetting the trailing edge 3 b of the gas barrier layer 3 at the positionin the lower end of the body 10 where the trailing edge 3 b does notreach the bottom 11′.

Preferred gas barrier materials include gas barrier resins, such as apolyamide containing m-xylylene diamine (known under the trade name ofMXD-6), which is used in the embodiment of this invention, and acopolymer of ethylene vinyl alcohol (EVOH); and the mixtures of thesegas barrier resins with oxygen-absorbing resins that are commonly usedin the form of inorganic or organic metal complexes containingtransition metal catalysts (e.g., Co, Fe, Mn, Ni, and Ti) in the matrixof aliphatic and aromatic nylons.

The embodiment of this invention shows two types of resins in threelayers comprising PET/Gas barrier/PET. It should be understood that thisinvention is not limited to this embodiment, but it is also possible touse a multilayer structure of two or three types of resins in fivelayers comprising, for instance, PET/Gas barrier/PET (including recycledmaterial)/Gas barrier/PET.

Industrial Applicability

This invention comprising the above-described configuration has thefollowing effects:

When the bottle according to the invention of claim 1 is molded, theleading edge of the gas barrier layer has been set at the position ofthe neck where the most advanced front of the leading edge neitherreaches a half height of the stop ring that is a part of the functionalportion of the neck nor extends to the functional portion of the neck,or has been set at a half height of the neck ring. This set position ofthe leading edge is not affected by the displacement of the leadingedge, which is sometimes observed inside the PET resin layers at thepreform-molding stage. After the whitening treatment of the neck, thebottle does not have to face the problem of the neck that shrinks lessand increases in dimensions, because the problem is caused simply by thedifference in the degrees of shrinkage between the PET resin and the gasbarrier material. Instead, the neck can be molded in the rightdimensions as designed.

In the invention of claim 2, the functional portion of the neck istreated for whitening without being affected altogether by the gasbarrier layer. Thus, after the whitening treatment, the functionalportion can be given the right dimensions as specified.

In the invention of claim 3, it is easy to set the position of theleading edge of the gas barrier layer, and the bottle can be moldedsafely while avoiding the impact of the gas barrier layer on the neck.

In the invention of claim 4, the trailing edge of the gas barrier layeris set at the position in the lower portion of the body where thetrailing edge does not reach the bottom. Therefore, no gas barrier layerexists in the bottom of the biaxially drawn, blow-molded bottle. Even ifthe bottle experiences the shock of a vertical load, such as the fall ofthe bottle, the bottle thus molded is free from any damaged transparencyand poor outer appearance that may be caused by the separation of thegas barrier layer from the PET resin layers at the bottom of the bottle.

In the invention of claim 5, the leading edge of the gas barrier layeris set at a half height of the stop ring, which is a part of thefunctional portion of the neck, or at a position of the neck where themost advanced front of the leading edge does not reach the functionalportion of the neck. In addition, the trailing edge of the gas barrierlayer is set at the position in the lower portion of the body. Thesesettings make it possible to mold the neck in the right dimensions asdesigned and to provide the biaxially drawn, blow-molded bottle whilecausing no separation between the gas barrier layer and the PET resinlayers and avoiding damaged transparency and poor outer appearance inthe bottom of the bottle even if there is a vertical load or the fall ofthe bottle.

When the preform according to the invention of claim 6 is molded, theleading edge of the gas barrier layer is positioned at a half height ofthe neck ring so that the most advanced front of the leading edgeneither reaches a half height of the stop ring nor extends to thefunctional portion of the neck. Because of this setting it is possible,after the whitening treatment, to mold the preform of a laminatedstructure that can be molded into the bottle with its neck having theright dimensions as designed.

When the preform according to the invention of claim 7 is molded, thetrailing edge of the gas barrier layer is set at the position where thetrailing edge does not reach the bottom. Therefore, it is possible tomold the preform that in turn can be molded into the biaxially drawn,blow-molded bottle without causing any damaged transparency and poorouter appearance even if the bottle experiences the shock of a verticalload, such as the fall of the bottle.

1. A biaxially drawn, blow-molded bottle comprising: at least a layer ofa gas barrier material laminated inside the layers predominantly made ofpolyethylene terephthalate; a functional portion having a screw threadraised spirally in the upper portion of neck and also having a stop ringdisposed under said screw thread; and a neck ring disposed at the lowerend of the neck, wherein the leading edge of said gas barrier layers isdisposed at a position of the neck where the most advanced front of theleading edge does not reach a half height of said stop ring and whereinthe neck is treated for thermal crystallization.
 2. The biaxially drawn,blow-molded bottle according to claim 1, wherein the leading edge ofsaid gas barrier layer is disposed at a position of the neck where themost advanced front of the leading edge does not reach the functionalportion.
 3. The biaxially drawn, blow-molded bottle according to claim1, wherein the leading edge of said gas barrier layer is disposed at aposition within a range of ±7 mm from a half height of the neck ring. 4.A biaxially drawn, blow-molded bottle comprising at least a layer of agas barrier material laminated inside layers predominantly made of apolyethylene terephthalate resin, wherein the trailing edge (3 b) ofsaid gas barrier layer is disposed in the lower portion of body wheresaid trailing edge does not reach bottom of said bottle.
 5. Thebiaxially drawn, blow-molded bottle according to claim 1, wherein thetrailing edge of said gas barrier layer is disposed in the lower portionof body where said trailing edge does not reach the bottom of saidbottle.
 6. Preform of a biaxially drawn, blow-molded bottle comprising:at least a layer of a gas barrier material laminated inside the layerspredominantly made of a polyethylene terephthalate resin; a functionalportion having a screw thread raised spirally in the upper portion ofneck and also having a stop ring disposed under said screw thread; and aneck ring disposed at the lower end of the neck, wherein the leadingedge of said gas barrier layer is positioned at a half height of theneck ring so that the most advanced front of the leading edge neitherreaches a half height of said stop ring nor extends to said functionalportion and wherein the neck is treated for thermal crystallization. 7.Preform of a biaxially drawn, blow-molded bottle comprising at least alayer of a gas barrier material laminated inside layers predominantlymade of a polyethylene terephthalate resin, wherein the trailing edge ofsaid gas barrier layer is disposed in the lower portion of body so thatsaid trailing edge does not reach the bottom of said bottle.
 8. Thebiaxially drawn, blow-molded bottle according to claim 2, wherein thetrailing edge of said gas barrier layer is disposed in the lower portionof body where said trailing edge does not reach the bottom of saidbottle.
 9. The biaxially drawn, blow-molded bottle according to claim 3,wherein the trailing edge of said gas barrier layer is disposed in thelower portion of body where said trailing edge does not reach the bottomof said bottle.